When feeding sheets against a reference edge, it is conventional to have rollers or other feeders canted toward the reference edge. Such feeding moves the sheet toward the reference surface, to thereby accurately position the sheet while primarily moving the sheet along the reference edge. Various designs of such feeders are known, such as illustrated in U.S. Pat. No. 4,982,946 to Uchimura.
Such prior designs, however, may not function well with a wide range of papers having different beam strength (stiffness). To positively move the heavier papers against the reference surface, the canted drivers must apply a force which will overcome the considerable drag which the heavier papers exhibit from passing over guide surfaces over which the papers passes during paper feed. When such strong forces are applied to light papers, the lighter papers are crushed against the reference edge surface and deformed. Consequently, current paper feeds in imaging apparatus are not universal, but instead feed sheets within a restricted range of stiffness. For example, paper feed which feed peel-off labels and card stock would not feed ordinary correspondence paper.
U.S. Pat. No. Re. 33,843 to Naramore et al and U.S. Pat. No. 4,179,117 to Rhodes, Jr. are feeders for a range of papers, termed here universal paper feeders. U.S. Pat. No. Re. 33,843 employs two idler rollers with an intermediate drive roller, all canted toward a reference surface. U.S. Pat. No. 4,179,117 employs backup and drive rollers in a nip, with the drive roller canted toward a reference edge and the backup roller canted away from the reference surface.